Interchanging barrels of XT to different receivers

I have a XT o/u and recently purchased a XT Unsingle.The Unsingle barrel seems to fit the o/u receiver okay but I have to use the forearm of the Unsingle because the forearm from o/u won't close. I didn't pull the triggers to see if the ejecters work or not. Does anyone see a problem with this?

I think a gunsmith is required to mate the locking block to the barrel lugs properly without causing excess stress to the gun. If you have 2 separate guns why would you mess around trying to fit the barrel from the unsingle onto the receiver of the O/U ? I added a Top single barrel to my MX-3 O/U but the gunsmith Phil Crenwelge fitted it so that the top lever is in the same position far to the right for either barrel set.

I had a XT combo and my un-single barrel would fit one persons receiver but not 2 others. Regardless of how they fit I would at least have a gunsmith look at it. An ounce of prevention is worth more than a pound of cure.